when a piezoelectric material experience a stress it generates voltage, and also when you applied voltage the piezo-material experience a vibrational frequency. Using oscilloscope we can determine the induced frequency of the piezo-material with respect to the applied voltage. Now given the dimensions of the material we can also determine the resonant/normal frequency of the material. My question is what is the frequency that detected by oscilloscope when you applied a voltage? is it the resonant frequency? or other form of frequency? then if so what is the relation of that detected frequency to the voltage and resonant frequency?